Bi-fold door assembly



Jan. 23, 1962 G. R. KAUPPILA BI-FOLD DOOR ASSEMBLY Filed May 5, 1959 Q Aa 7/: i m

INVENTOR GEORGE R. KAUPPILA ATTORNEYS The present invention relates toimprovements in bi-. fold doors, and more particularly to improvedhardware therefor.

In the bi-fold door art the most common hardware for collapsing the doorcomprises a guide track mounted on the door frame header and a followermounted on the head rail of the door adjacent its travelling edge. Sucha door collapses responsive to a pull adjacent the hinged center thereofand is normally restricted to a 90 degree opening.

The present invention aims to provide effective bi-fold door hardware ofmore simple and economical construction which does not require the useof a guide track and which will readily swing open 180 degrees.

A further invention is to provide such improved bifold door hardwarewhich will spring-hold the door in both its open and closed positionswithout the use of auxiliary springs.

Other more particular objects and advantages will, together with thesegeneral objects, appear and be understood in the course of the followingdescription and claims, the invention consisting in the novelconstruction and in the adaptation and combination of parts hereinafterdescribed and claimed.

In the accompanying drawings:

FIG. 1 is a fragmentary horizontal sectional view of a bi-fold doorequipped with the present invention and taken at the top of the door.

FIG. 2 is a fragmentary vertical sectional view taken as indicated bythe line 2--2 of FIG. 1.

FIG. 3 is a detail elevational view partly in section of one end of theswing arm and with the related bracket shown fragmentarily.

FIG. 4 is a top detail view illustrating the meeting arrangement betweena pair of the bi-fold doors and taken similarly to FIG. 1; and

FIG. 5 is a fragmentary vertical sectional view taken as indicated byline 5-5 of FIG. 4.

Referring to the drawings, for purposes of example, I have shown abi-fold door in mounted by butt hinges 311 on a side jamb'll3 of adoorway and having its inner and outer sections flitta-ltlb hingedtogether by butt hinges 12 to collapse or fold forwardly. For a reasonother than forward collapsing, to be later detailed, the knuckles orbarrels 12a of hinges 12 are purposely set back from the rear face ofthe door. The barrels liia of hinges 11, on the other hand, are setforwardly to permit an 80 degree swing of the inner door section.

Folding of the door is controlled by a swing arm 14 which is bent at anelbow l5 defining humerus and forearm portions 16li7. The swing arm isfabricated from steel rod stock or some other suitable material whichwill provide adequate spring flexure at the elbow. As shown for theouter end of the arm 114 in FIG. 3, both ends thereof are bunched from around to a square crosssection and kerfed endwise to form forks 13 atthe free ends of the humerus l6 and forearm 17. These forks are suitablybored and tapped to have their gaps bridged by the enlarged shankportions 21 of respective necked pivot pins 19-20 each having a threadedneck 22 and a slotted head 23. The pins -192t are used to pivotallymount the forked terminal ends of the humerus and f0re arm on theflanges of Z and angle bracket 24-25, respectively, the Z bracket beingsuspended from the head at fire saunas Patented Jan. 23, 1962 jamb 26and the angle bracket being mounted on the back of the outer doorsection 10b adjacent its head.

The spring-holding affects, at both the open and closed positions of thedoor, the included angle at the elbow between the humerus and theforearm is increased by elbow flexure at said positions over thecorresponding angle when the swing arm is in a relaxed condition.Freedom from spring loading is achieved through a large part of the doortravel by making the lineal distance between the axes of the pivotsrace, when the swing arm is relaxed, substantially equal to the linealdistance between the swing axes of the hinges 11li2. In this manner aparallel action results between the swing axes of the door sections andthe pivotal axes at the ends of the swing arm during swing travel of thedoor sections between the initial point of contact at the free edge ofthe outer section Citib with the head jamb (position #2 in FIG. 1) andthe point of contact of the forearm portion 17 with the inner doorsection 10a (position #4). In most installations it is found desirableto have position #2 occur fairly close to the fully closed position #1,and such can be readily adjusted by shifting the brackets 24-25 relativeto the hinges 11-12.

With the swing arm partaking of relaxed parallel action betweenpositions #2 and #4, as illustrated by position #3, it can be seen thatif the door is closed further than position #2, the parallel actionceases because the free side edge of the outer door section 19b mustthereafter slide along the head jamb stop 27 rather than continuing toswing. Thus further closing of the door can only continue by gradualincrease of the lineal distance between the pins 1920. This increase isachieved by spring flexure of the swing arm at its elbow 15. It isimportant, as before mentioned, to note that by the time the doorreaches its fully closed position the axis of hinges 12 has movedslightly behind a straight line drawn between the pivotal axes at theends of the swing arm. By this arrangement the swing arm in attemptingto relax from its flexed or tensioned condition keeps the door sprungclosed since its tendency has become one of urging the door sections tofold or collapse rearwardly rather than forwardly.

Returning to position #4 and namely that corresponding to the firstpoint of contact between the forearm 17 and the inner door section 10a,it can readily be seen that further swinging of the door toward the walladjoining the doorway can only be accomplished by again spring flexingthe elbow 15 to increase the included angle and thereby increase thestraight line distance between the pins l9-2tl. Of importance to note isthe fact that when the door has swung far enough toward fully openposition #4 to bring a line drawn between pins 19-26 behind the swingaxis of hinges 11, maximum flexure of the swing arm has been reached,and hence the door will thereupon be spring urged toward position #4.Thus it is seen that the door is spring-held in both its open and closedpositions by flexure of the swing arm.

From an inspection of position #5 it can be seen that the humerusportion 16 of the swing arm must be made long enough to permit theforearm 17 to swing into substantially parallel relation to the wallwhile taking into account the thickness of the door sections and theoffset of the barrels of the hinges llll. At the same time the brackets24-45 must be located far enough from the hinges 11-12 to make thedistance from the pin 2% to the free edge ofthe outer door section litbless than the length of the forearm 17. In this regard, it can be seenthat the further the pin 19 is displaced laterally of the doorway fromthe adjacent side jamb, the greater can be the included angle at theelbow 15. Increase of this angle may be important in some installationsto keep the rearward displacement of the elbow 15 to a minimum at thefully closed position of the door. For example, in FIGURES 1-2 I haveshown an arrangement wherein the stop 27 of the head jamb is a separatepiece having its upper face rabbeted to provide a chamber 23 for housingthe swing arm when the door is closed.

To pull the door open there is provided a handle 29 which is preferablylocated on the front face of th outer door section b between its hingededge and a vertical cross-sectional plane through the pivot pin 23. Pullon a handle so located tends to immediately collapse the door forwardlyand leaves the handle exposed when the door is in its fully openposition.

If the door is located in a passageway as distinguished from a closetopening, provision is made to resist pushing action by a person appliedadjacent the free edge of the outer door section 10b since such wouldhave the undesirable tendency to urge the door to collapse rear- Wardlyrather than forwardly. This resistance is accomplished by mounting amale fitting 31 on the swing jamb 30 forwardly of its stop and boring amating hole 32 in the corresponding stile of the outer door section 1012at the same height from the floor. The hole 32. must be slightly largerin diameter, particularly at the mouth, than the fitting 31 toallow forthe pivoting of the free side edge of the door as it slides at the topalong the stop of the head jamb from position #2 to the fully closedposition. At the latter, the fitting 31 by being lodged in the hole 32will resist forward pushing of the door if applied toward the swing jamb30 from the pivotal axis of the pin 20. A handle may be placed on theback side of the door opposite the handle 28 if desired to indicate theproper push point. Such a handle should not project rearwardly fartherthan twice the offset of the swing axis of the hinges 11 so as not tointerfere with complete opening of the door.

In extra wide openings it may be desired to mount a pair of bi-folddoors 10A10B meeting in the center. To resist one of such a pair frombeing pulled forwardly by a grip on its free edge when the other door isopen, and to resist forward pushing from the back side near the centerof the opening, the hole 32 of each door is placed close to its upperend and in alinement with that of the other. As shown in FIGURES 45, themembers 31a for these holes are secured at opposite sides of a thintwo-ply mounting plate 33 which projects forwardly between the meetingedges of the doors from the head jamb stop, denoted 34, and has a loopedroot end portion 33a. The latter can be mortised into the stop and themortise filled by filler 35.

Thus it is seen that I have provided a versatile bi-fold door assemblyof simple and economical construction in which a swing arm functions notonly to collapse the door, but also to spring-hold the door in both itsopen and closed positions.

The advantages of the invention, it is thought, will have been clearlyunderstood from the foregoing detailed description of the illustratedpreferred embodiment. Minor changes will suggest themselves and may beresorted to without departing from the spirit of the invention,wherefore it is my intention that no limitations be implied and that thehereto annexed claims be given a scope fully commensurate with thebroadest interpretation to which the employed language admits.

What I claim is:

1. A bi-fold door assembly comprising, a door frame, inner and outerbi-fold door sections hingedly connected together to collapse in aforward direction, said inner section being hingedly connected to a sidejamb of said door frame for forward swinging movement between open andclosed positions, and a bent one-piece swing arm adapted to flex andpivotally mounted at its ends to the back of said outer section and tosaid door frame for swinging movement, said end pivots of the swing armbeing spaced apart when said door is in its said closed position adistance greater than when said door is partly open.

2. The structure of claim 1 in which the hinge axis between said doorsections is located rearwardly of a line connecting said end pivots ofthe swing arm when said door is in said closed position.

3. A bifold door assembly comprising, a door frame,

inner and outer bi-fold door sections hingedly connectedtogether tocollapse in a forward direction, said inner section being hingedlyconnected to a slide jamb of said door frame for forward swingingmovement between open and closed positions, and a bent one-piece swingarm adapted to flex and pivotally mounted at its ends to the back ofsaid outer section and to said door frame for swinging movement, saidend pivots of the swing arm being spaced apart when said door is in itssaid open position a distance greater than when said door is only partlyopen.

4. The structure of claim 2 in which the hinge axis between said innersection and said side arm is located forwardly of a line connecting saidend pivots of the swing arm when said door is in said open position.

5. A bi-fold door assembly comprising, a door frame, inner and outer-bi-fold door sections hingedly connected together to collapse in aforward direction, said inner section being hingedly connected to a sidejamb of said door frame for forward swinging movement between open andclosed positions, and a bent one-piece swing arm adapted to flex andpivotally mounted at its ends to the back of said outer section and tosaid door frame for swinging movement, said end pivots of the swing armbeing spaced apart when said door is in its said closed and openpositions respective distances each of which is greater than when saiddoor is intermediate said positions.

6. The structure of claim 5 in which the hinge axis between said doorsections is located rearwardly of a line connecting said end pivots ofthe swing arm when said door is in said closed position, and in whichthe hinge axis between said inner section and said side jamb is locatedforwardly of a line connecting said end pivots of the swing arm whensaid door is in said open position.

References fitted in the file of this patent UNITED STATES PATENTS563,058 Peck June 30, 1896 1,000,707 Borg Aug. 15, 1911 2,014,591Sanders Sept. 17, 1935 2,725,099 Frie et a1. Nov. 29, 1955 2,763,900McAfee et al. Sept. 25, 1956

